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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 42 |
| 4 | 260 |
| 5 | 1796 |
| 6 | 13396 |
| 7 | 105706 |
| 8 | 870772 |
| 9 | 7420836 |
| 10 | 65004584 |
| 11 | 582521748 |
| 12 | 5320936416 |
| 13 | 49402687392 |
| 14 | 465189744448 |
| 15 | 4434492302426 |
| 16 | 42731740126228 |
| 17 | 415736458808868 |
| 18 | 4079436831493480 |
| 19 | 40338413922226212 |
| 20 | 401652846850965808 |
| 21 | 4024556509468827432 |
| 22 | 40558226664529024000 |
| 23 | 410887438338905738908 |
| 24 | 4182776248940752113344 |
| 25 | 42770152711524569532616 |
| 26 | 439143340987014152920384 |
| 27 | 4526179842103708969039296 |
[1,2,8,42,260,1796,13396,105706,870772,7420836, 65004584,582521748,5320936416,49402687392, 465189744448,4434492302426,42731740126228, 415736458808868,4079436831493480, 40338413922226212,401652846850965808, 4024556509468827432,40558226664529024000, 410887438338905738908,4182776248940752113344, 42770152711524569532616,439143340987014152920384, 4526179842103708969039296] |